Effect and mechanism of essential oil from Zanthoxylum bungeanum in microemulsion gel preparation on percutaneous delivery of complex components

Abstract

This study aimed to investigate the transdermal enhancing effect of essential oil from Zanthoxylum bungeanum(Z. bungeanum oil) in microemulsion gel(ZO-ME-gel) on permeation of different components,and reveal the transdermal enhancing mechanism of ZO-ME-gel. A series of components with different log P values were selected as model drugs and encapsulated in ZO-ME-gel to simplify and characterize the complex components of traditional Chinese medicine. The transdermal behavior of the model drugs was further examined using the improved Franz diffusion cell method. Then attenuated total reflection Fourier transform infrared spectroscopy(ATR-FTIR),differential scanning calorimetry(DSC) studies and hematoxylin-eosin(HE) staining were used to investigate the effects of Z. bungeanum oil and ZO-ME-gel on keratin,intercellular lipids and microstructure of the stratum corneum(SC). The results showed that Z. bungeanum oil and ZO-ME-gel had a good transdermal enhancing effect on both hydrophilic and lipophilic drugs,and the best effect was achieved when log P value was-0. 5. The transdermal enhancing mechanism of Z. bungeanum oil and ZO-ME-gel was related to affecting the order of the SC lipids,changing lipid fluidity and protein conformation,and disrupting the integrity of the SC structure. 5% Z. bungeanum oil had greater transdermal enhancing effect and destruction of SC structure than ZO-ME-gel. These results suggested that Z. bungeanum oil loaded in microemulsion gel still had a good transdermal enhancing effect although the effect was not as great as Z. bungeanum oil itself,in addition,ZO-ME-gel was less irritating to the skin and safer to use,which had a guiding role in the development and clinical application of Z. bungeanum oil-containing traditional Chinese medicine topical preparations.